listeriosis

Listeriosis

Definition

Listeriosis is an illness caused by the bacterium Listeria monocytogenes that is acquired by eating contaminated food. The organism can spread to the blood stream and central nervous system. During pregnancy, listeriosis often causes miscarriage or stillbirth.

Description

Listeriosis is caused by an infection with the bacterium Listeria monocytogenes. This bacteria can be carried by many animals and birds, and it has been found in soil, water, sewage, and animal feed. Five out of every 100 people carry Listeria monocytogenes in their intestines. Listeriosis is considered a "food-borne illness" because most people are probably infected after eating food contaminated with Listeria monocytogenes. However, a woman can pass the bacteria to her baby during pregnancy. In addition, there have been a few cases where workers have developed Listeria skin infections by touching infected calves or poultry.

In the 1980s, the United States government began taking measures to decrease the occurrence of listeriosis. Processed meats and dairy products are now tested for the presence of Listeria monocytogenes. The Food and Drug Administration (FDA) and the Food Safety and Inspection Service (FSIS) can legally prevent food from being shipped, or order food recalls, if they detect any Listeria bacteria. These inspections, in combination with the public education regarding the proper handling of uncooked foods, appear to be working. In 1989, there were 1,965 cases of listeriosis with 481 deaths. In 1993, the numbers fell to 1,092 cases with 248 deaths.

In 1996, the Centers for Disease Control and Prevention (CDC) began a nationwide food-borne disease surveillance program called "FoodNet," in which seven states were participating by January 1997. Results from the program indicated that, in 1996, one person out of every 200,000 people got listeriosis. FoodNet also revealed that the hospitalization rate was higher for listeriosis (94%) than for any other food-borne illness. In addition, FoodNet found that the Listeria bacteria reached the blood and cerebrospinal fluid in 89% of cases, a higher percentage than in any other food-borne illness.

Persons at particular risk for listeriosis include the elderly, pregnant women, newborns, and those with a weakened immune system (called "immunocompromised"). Risk is increased when a person suffers from diseases such as AIDS, cancer, kidney disease, diabetes mellitus, or by the use of certain medications. Infection is most common in babies younger than one month old and adults over 60 years of age. Pregnant women account for 27% of the cases and immunocompromised persons account for almost 70%. Persons with AIDS are 280 times more likely to get listeriosis than others.

Causes and symptoms

As noted, persons become infected with Listeria monocytogenes by eating contaminated food. Listeria has been found on raw vegetables, fish, poultry, raw (unpasteurized) milk, fresh meat, processed meat (such as deli meat, hot dogs, and canned meat), and certain soft cheeses. Listeriosis outbreaks in the United States since the 1980s have been linked to cole slaw, milk, Mexican-style cheese, undercooked hot dogs, undercooked chicken, and delicatessen foods. Unlike most other bacteria, Listeria monocytogenes does not stop growing when food is in the refrigerator - its growth is merely slowed. Fortunately, typical cooking temperatures and the pasteurization process do kill this bacteria.

Listeria bacteria can pass through the wall of the intestines, and from there they can get into the blood stream. Once in the blood stream, they can be transported anywhere in the body, but are commonly found the central nervous system (brain and spinal cord); and in pregnant women they are often found in the placenta (the organ which connects the baby's umbilical cord to the uterus). Listeria monocytogenes live inside specific white blood cells called macrophages. Inside macrophages, the bacteria can hide from immune responses and become inaccessible to certain antibiotics. Listeria bacteria are capable of multiplying within macrophages, and then may spread to other macrophages.

After consuming food contaminated with this bacteria, symptoms of infection may appear anywhere from 11-70 days later. Most people do not get any noticeable symptoms. Scientists are unsure, but they believe that Listeria monocytogenes can cause upset stomach and intestinal problems just like other foodborne illnesses. Persons with listeriosis may develop flu-like symptoms such as fever, headache, nausea and vomiting, tiredness, and diarrhea.

Pregnant women experience a mild, flu-like illness with fever, muscle aches, upset stomach, and intestinal problems. They recover, but the infection can cause miscarriage, premature labor, early rupture of the birth sac, and stillbirth. Unfortunately, half of the newborns infected with Listeria will die from the illness.

There are two types of listeriosis in the newborn baby: early-onset disease and late-onset disease. Early-onset disease refers to a serious illness that is present at birth and usually causes the baby to be born prematurely. Babies infected during the pregnancy usually have a blood infection (sepsis) and may have a serious, whole body infection called granulomatosis infantisepticum. When a full-term baby becomes infected with Listeria during childbirth, that situation is called late-onset disease. Commonly, symptoms of late-onset listeriosis appear about two weeks after birth. Babies with late-term disease typically have meningitis (inflammation of the brain and spinal tissues); yet they have a better chance of surviving than those with early-onset disease.

Immunocompromised adults are at risk for a serious infection of the blood stream and central nervous system (brain and spinal cord). Meningitis occurs in about half of the cases of adult listeriosis. Symptoms of listerial meningitis occur about four days after the flu-like symptoms and include fever, personality change, uncoordinated muscle movement, tremors, muscle contractions, seizures, and slipping in and out of consciousness.

Listeria monocytogenes causes endocarditis in about 7.5% of the cases. Endocarditis is an inflammation of heart tissue due to the bacterial infection. Listerial endocarditis causes death in about half of the patients. Other diseases which have been caused by Listeria monocytogenes include brain abscess, eye infection, hepatitis (liver disease), peritonitis (abdominal infection), lung infection, joint infection, arthritis, heart disease, bone infection, and gallbladder infection.

Diagnosis

Listeriosis may be diagnosed and treated by infectious disease specialists and internal medicine specialists. The diagnosis and treatment of this infection should be covered by most insurance providers.

The only way to diagnose listeriosis is to isolate Listeria monocytogenes from blood, cerebrospinal fluid, or stool. A sample of cerebrospinal fluid is removed from the spinal cord using a needle and syringe. This procedure is commonly called a spinal tap. The amniotic fluid (the fluid which bathes the unborn baby) may be tested in pregnant women with listeriosis. This sample is obtained by inserting a needle through the abdomen into the uterus and withdrawing fluid. Listeria grows well in laboratory media and test results can be available within a few days.

Treatment

Listeriosis is treated with the antibiotics ampicillin (Omnipen) or sulfamethoxazole-trimethoprim (Bactrim, Septra). Because the bacteria live within macrophage cells, treatment may be difficult and the treatment periods may vary. Usually, pregnant women are treated for two weeks; newborns, two to three weeks; adults with mild disease, two to four weeks; persons with meningitis, three weeks; persons with brain abscesses, six weeks; and persons with endocarditis, four to six weeks.

Patients are often hospitalized for treatment and monitoring. Other drugs may be provided to relieve pain and fever and to treat other reactions to the infection.

Prognosis

The overall death rate for listeriosis is 26%. This high death rate is due to the serious illness suffered by newborns, the elderly, and immunocompromised persons. Healthy adults and older children have a low death rate. Complications of Listeria infection include: meningitis, sepsis, miscarriage, stillbirth, pneumonia, shock, endocarditis, abscess (localized infection) formation, and eye inflammation.

Prevention

The United States government has already done much to prevent listeriosis. Persons at extremely high risk (pregnant women, immunocompromised persons, etc.) must use extra caution. High risk persons should: avoid soft cheeses, such as Mexican cheese, feta, Brie, Camembert, and blue cheese (cottage cheese is safe), thoroughly cook leftovers and ready-to-eat foods (such as hot-dogs), and avoid foods from the deli.

For all people, the risk of listeriosis can be reduced by taking these precautions:

Completely cook all meats and eggs.

Carefully wash raw vegetables before eating.

Keep raw meat away from raw vegetables and prepared foods. After cutting raw meat, wash the cutting board with detergent before using it for vegetables.

Resources

Other

Key terms

Abscess — An accumulation of pus caused by localized infection in tissues or organs. Listeria monocytogenes can cause abscesses in many organs including the brain, spleen, and liver.

Immunocompromised — To have a poor immune system due to disease or medication. Immunocompromised persons are at risk for developing infections because they can't fight off microorganisms like healthy persons can.

Macrophages — White blood cells whose job is to destroy invading microorganisms. Listeria monocytogenes avoids being killed and can multiply within the macrophage.

Meningitis — An inflammation of the tissues that surround the brain and spinal cord. It can be caused by a bacterial infection.

Sepsis — The presence of bacteria in the blood stream, a normally sterile environment.

listeriosis

[lis-tēr″e-o´sis]

infection caused by Listeria monocytogenes. In humans, in utero infections occur transplacentally and result in abortion, stillbirth, and premature birth; infections acquired during birth cause cardiorespiratory distress, diarrhea, vomiting, and meningitis. Infection in adults produces meningitis, endocarditis, and disseminated granulomatous lesions. Infection in cattle and sheep causes encephalitis and abortion. Nervous signs are common in ruminants, and necrosis of the liver in monogastric animals. Because affected animals tend to move in circles, it is also known as circling disease.

listeriosis

(lĭ-stîr′ē-ō′sĭs)

n.

Infection with the bacterium Listeria monocytogenes, characterized in humans by fever, gastrointestinal symptoms, and sometimes headache and convulsions, and in pregnant women often leading to miscarriage or stillbirth. In domestic animals it can cause encephalitis, septicemia, and abortion. The bacterium occurs as a contaminant in raw or improperly processed foods.

listeriosis

[listir′ē·ō′sis]

Etymology: Joseph Lister; Gk, osis, condition

an infectious disease caused by a genus of gram-positive motile bacteria that are nonsporulating. Listeria monocytogenes infects shellfish, birds, spiders, and mammals in all areas of the world, but infection in humans is uncommon. It is transmitted by direct contact between infected animals and humans, through the ingestion of contaminated meat and dairy products, by inhalation of dust, or by contact with mud, sewage, or soil contaminated with the organism. The disorder is characterized in mild cases by fever, myalgia, nausea, and diarrhea and in severe cases by circulatory collapse, shock, endocarditis, hepatosplenomegaly, and a dark red rash over the trunk and legs. Fever, bacteremia, malaise, and lethargy are commonly seen. Newborns and immunosuppressed debilitated older people are more vulnerable to infection than are immunocompetent children and young or middle-aged adults. The signs of infection and the severity of the disease vary according to the site of infection and the age and condition of the person. Pregnant women characteristically experience a mild brief episode of illness, but fetal infection acquired through the placental circulation in utero is usually fatal. Infection in the newborn apparently results from exposure to the organism in the birth canal of an infected mother. Meningitis and encephalitis occur in 75% of cases. Treatment may include ampicillin, penicillin, tetracycline, or erythromycin given intramuscularly or intravenously. Trimethoprim-sulfamethoxazole is an alternative. If infection is suspected in a pregnant woman, treatment is begun immediately, even before bacteriological culture of the blood, spinal fluid, or vaginal secretions can confirm the diagnosis. All secretions from the patient may contain the organism. Also called listerosis.

lis·ter·i·o·sis

(lis-tēr'ē-ō'sis)

A sporadic disease of animals and humans, particularly those who are immunocompromised or pregnant, caused by a bacterium, Listeria monocytogenes.

[fr. organism Listeria]

listeriosis

An infection with the organism, Listeria monocytogenes , which is found in most meats, poultry, fish, crustaceans and in soft cheeses and various precooked foods. Proper cooking will kill the organism which, however, varies considerably in its ability to cause disease (virulence). Listeriosis is commonest in babies and old people and most cases are mild and pass unremarked. Severe cases feature fever, CONJUNCTIVITIS, inflammation of the salivary glands as in mumps, sometimes skin pustules and, rarely, arthritis, bone inflammation and abscesses in the brain and spinal cord. Listeriosis responds well to PENICILLIN, ERYTHROMYCIN and TETRACYCLINE.

listeriosis

an infectious disease affecting all species and caused by Listeria monocytogenes which can multiply in silage above pH 5.0-5.5 so that listeriosis in animals is commonly associated with feeding poorly prepared silage. In the northern hemisphere, listeriosis has a distinct seasonal occurrence associated with seasonal feeding of poorly preserved silage, with the highest prevalence in the months of December through May. Listeriosis is characterized by a number of syndromes: Encephalitis usually has sporadic occurrence and presents with unilateral brain stem and cranial nerve dysfunction, circling, facial paralysis, head pressing, and death following a short clinical course. Called also listerial meningoencephalitis. Abortion is late term, sporadic in cattle but can occur as an outbreak in small ruminants. Has zoonotic risk to pregnant females lambing out the flock Uveitis/ophthalmitis occurs in both sheep and cattle and can occur as an outbreak. Many but not all outbreaks have been associated with round bale 'self-feed' silage in the winter period where infected silage can directly contaminate the eye. Called also silage eye. Septicemic disease is a less common manifestation but can occur as an outbreak with a high case fatality in newborn lambs and kids and also in periparturient ewes and does. Spinal myelitis may occur in sheep following dipping and spontaneously in cattle, but is uncommon. Gastroenteritis may occur in sheep of all ages, 2 days after the start of feeding on infected silage. Mastitis occurs but is uncommon. It can result in contamination of bulk milk with L. monocytogenes but the more common source is fecal contamination.

Despite the efforts that have been made by food industries and sanitary authorities, listeriosis outbreaks are still being notified in Europe and Unites States and it is possible that it tends to rise as the number of individuals elderly and immunocompromised increases, as well as pregnant women and children, are more susceptible to this disease (SLUTSKER et al.

After the market withdrawal and recall, CDC fielded > 450 inquiries about listeriosis from concerned consumers and clinicians, and the CDC outbreak website received [greater than or equal to] 787,000 page views, more views than after any other foodborne illness outbreak to date.

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